A. Field of the Invention
The field of the present invention relates generally to apparatuses and methods for filtering fluid, such as oil from internal combustion engines, to remove particulate and liquid contaminants from the fluid. More particularly, the present invention relates to such apparatuses and methods which use centrifugal separators to separate liquid, corrosive, particulate and/or volatile contaminants from fluid and routing the contaminants into easily emptied collection tanks. Even more particularly, the present invention relates to such apparatuses and methods which utilize separate tanks or compartments to filter and store contaminants from the fluid.
B. Background
As is well known, internal combustion engines and other mechanical equipment and machines require lubrication of the moving components to prevent damage and premature wear to the engine or machine. Generally, engines and other machines have a lubrication fluid circulating system that coats the moving components with a thin layer of lubricant. During circulation of the lubricating fluid through the machine, the fluid is exposed to, absorbs and carries a variety of liquid, particulate and volatile contaminants. Because these contaminants can significantly reduce the ability of the lubricant to provide the required lubricating effect and, as a result be a hazard to engine life and performance and increase emissions from such engines, it is necessary to filter the lubricant to remove as much of the contaminants as possible in order to maintain lubrication purity. In motor vehicles and other equipment having internal combustion engines, the most common type of lubricant is oil and the most common filter is a full-flow filter that attaches to the oil pan or sump of the engine to remove contaminants from the flowing lubrication stream. Presently, the most widely accepted and utilized method of maintaining oil purity and quality in internal combustion engines is to frequently and periodically change, by removing and replacing, the oil and oil filter.
Although removing contaminated oil and filters is necessary and effective, replacing the oil and filter as a means to maintain oil quality has many drawbacks. The cost of replacing the oil and filters, as well as the labor involved, over the life of the engine or machine is considerable. In addition, other related expenses, in many industries, include hazardous waste removal costs and government fees and hazardous waste liability insurance. During the intervals between oil changes, contaminants are progressively building up in the oil, and during this time, can cause damage and increase emissions. Although the oil and filter are removed, much of the contamination is left in the crank case, as well as the bottom of the oil pan, to be circulated into the new oil when it is introduced into the system. Additionally, the effect of the new filter is limited, in that standard full-flow filters are designed to remove only the largest of particles and do little or nothing to remove other types of contaminants, such as water, corrosives, volatile contaminants and small particles, all of which are considered damaging to the life and performance of the engine. Based on this well known problem, the obvious solution would seem to be enhanced filtering of the oil during circulation through the engine.
Thus far, the market for enhanced filtering systems has not shown itself to be very broad. The expense associated with replacement of these filtering elements is one major issue, and the disposal of the rather large, used filter media is another. Also, these systems can easily become clogged with the contaminants they are configured to remove from the lubricating fluid. Although an improvement in lubrication fluid purity by these devices and methods has been demonstrated, they do not address the issue of volatile build-up in the oil, which can decrease viscosity. This is a major concern for the owner of an internal combustion engine who expects to run that engine on the same oil for any extended period of time, as the decrease in viscosity can lead to less effective lubrication. Insofar as these methods can keep oil cleaner, this benefit is of little value when the oil or other lubricating fluid being filtered loses viscosity, which oil and other lubricants are well known to do after extended periods of use at high temperatures (as found in internal combustion engines). The expense associated with the known enhanced filtering systems becomes difficult to justify, when taking into consideration the now viscosity-limited life of the oil, which is the original reason for utilizing the filtering system to keep it clean.
Many attempts have been made to bring to market less expensive and more efficient apparatuses for maintaining oil purity and quality in order to extend lubricating fluid life. Larger more dense filter media and disposable filters that last longer and increase purification have been proposed. Other forms of separation have been attempted and, in certain applications, have been cost effective improvements over previously used methods. One area which appears to be the most promising, for the purpose of extending the life of oil, is centrifugal separation. Patents have been granted for devices intended to remove contaminants from oil through centrifugal force. A couple of examples pertinent to the present invention are U.S. Pat. No. 6,423,225 to Wong et al and U.S. Pat. No. 4,640,772 to Graham.
The patent to Wong describes a liquid filter having a centrifugal separator with an annular filter element and a series of slanted fins at the main entrance to the housing which are intended to encourage the fluid travel in a specific direction, that being the outer walls of the filter housing, before the fluid travels through the filter element that is located at the center of the device. The filter is configured such that the heavier, separated contaminants are intended to move against the inside of the outer walls of the housing and accumulate at the bottom of the housing below the filter element. Although the device appears to be able to extend the life of the filter, by removing particles from the fluid to be filtered, it does not necessarily extend engine oil life as it provides no mechanism for removing volatiles from the lubricating fluid. Another limitation with this filter is the likely creation of turbulence within the filter, for which no solution or control is offered. Turbulence within the filter system results in the reintroduction of the contaminants to the flow of fluid, causing them to be returned to the general fluid circulation, which would tend to reduce the reduce the possibility of extended filter life.
The oil assembly detailed in the patent to Graham is also based on the concept of centrifugal force to separate contaminants from lubricating oil. This assembly seeks to create enough centrifugal force, through the use of a preferably disposable rotor, to separate the contaminants from the oil. As with the patent to Wong, however, the patent to Graham does not address the volatile issue, nor does it address the issue of turbulence control in order to prevent the reintroduction of contaminants to the oil. Another apparent limitation of this device is that the contaminants that are separated by being forced against the walls of the housing appear to only maintain their separation for as long as the rotor is kept turning. Because the rotor is kept turning by the circulation of the engine oil, the logical assumption is that upon turning the motor off, the sludge and other contaminants would run to the bottom of the unit. Unfortunately, the unit is designed to return oil from the bottom of the rotor directly back to the engine, and also bleed off to the filter element below, thereby reducing the effectiveness of all the rotor turning and separation of elements for oil purification and extension of filter life.
What is needed, therefore, is a relatively low cost, effective and easy to utilize apparatus and method for removing contaminates, including liquid, particulate and volatile contaminants, from a fluid, such as lubricating oil or any other fluid having particulate matter and/or one or more contaminating fluids of a different specific gravity than the clean fluid. The optimum solution would be a system that uses centrifugal separation, with specifically stratified and directed removal of all contaminants. This would allow for lighter volatile removal, as well as removal of water, corrosives and particulate matter. Such a system would also result in greatly extended filter life. Another requisite for such a device would be a system of pressure balances and baffles to control flow and turbulence within the filter. The preferred filter should also include one or more reusable, accessible collection tanks or compartments for ease in removal of each class of contaminant. Such as system would effectively serve as a compact, onboard refinery for the lubricating oil or other fluid.